Add PAuth helpers for signing, stripping and authentication of pointers

droe · droe · commit 36cd5df49ca9 · 2025-11-17T23:26:51.000+01:00
Add UC_CTL_PAUTH_SIGN, UC_CTL_PAUTH_STRIP and UC_CTL_PAUTH_AUTH as an
architecture-independent interface to pointer authentication operations
without having to execute instructions on the virtual CPU.  This is
useful in many scenarios, for instance when rebasing signed pointers as
part of loading code that runs with PAuth.

The C interfaces are covered by a unit test.  The Python interfaces have
been tested in a real world project.
diff --git a/bindings/dotnet/UnicornEngine/Const/Arm64.fs b/bindings/dotnet/UnicornEngine/Const/Arm64.fs
@@ -340,3 +340,12 @@ module Arm64 =
     let UC_ARM64_INS_WFI = 5
     let UC_ARM64_INS_ENDING = 6
 
+    // ARM64 PAuth keys
+
+    let UC_ARM64_PAUTH_KEY_IA = 0
+    let UC_ARM64_PAUTH_KEY_IB = 1
+    let UC_ARM64_PAUTH_KEY_DA = 2
+    let UC_ARM64_PAUTH_KEY_DB = 3
+    let UC_ARM64_PAUTH_KEY_GA = 4
+    let UC_ARM64_PAUTH_KEY_ENDING = 5
+
diff --git a/bindings/dotnet/UnicornEngine/Const/Common.fs b/bindings/dotnet/UnicornEngine/Const/Common.fs
@@ -152,6 +152,9 @@ module Common =
     let UC_CTL_TLB_TYPE = 12
     let UC_CTL_TCG_BUFFER_SIZE = 13
     let UC_CTL_CONTEXT_MODE = 14
+    let UC_CTL_PAUTH_SIGN = 15
+    let UC_CTL_PAUTH_STRIP = 16
+    let UC_CTL_PAUTH_AUTH = 17
     let UC_CTL_CONTEXT_CPU = 1
     let UC_CTL_CONTEXT_MEMORY = 2
 
diff --git a/bindings/go/unicorn/arm64_const.go b/bindings/go/unicorn/arm64_const.go
@@ -334,4 +334,13 @@ const (
 	ARM64_INS_SYSL = 4
 	ARM64_INS_WFI = 5
 	ARM64_INS_ENDING = 6
+
+// ARM64 PAuth keys
+
+	ARM64_PAUTH_KEY_IA = 0
+	ARM64_PAUTH_KEY_IB = 1
+	ARM64_PAUTH_KEY_DA = 2
+	ARM64_PAUTH_KEY_DB = 3
+	ARM64_PAUTH_KEY_GA = 4
+	ARM64_PAUTH_KEY_ENDING = 5
 )
diff --git a/bindings/go/unicorn/unicorn_const.go b/bindings/go/unicorn/unicorn_const.go
@@ -147,6 +147,9 @@ const (
 	CTL_TLB_TYPE = 12
 	CTL_TCG_BUFFER_SIZE = 13
 	CTL_CONTEXT_MODE = 14
+	CTL_PAUTH_SIGN = 15
+	CTL_PAUTH_STRIP = 16
+	CTL_PAUTH_AUTH = 17
 	CTL_CONTEXT_CPU = 1
 	CTL_CONTEXT_MEMORY = 2
 )
diff --git a/bindings/java/src/main/java/unicorn/Arm64Const.java b/bindings/java/src/main/java/unicorn/Arm64Const.java
@@ -337,4 +337,13 @@ public interface Arm64Const {
     public static final int UC_ARM64_INS_WFI = 5;
     public static final int UC_ARM64_INS_ENDING = 6;
 
+    // ARM64 PAuth keys
+
+    public static final int UC_ARM64_PAUTH_KEY_IA = 0;
+    public static final int UC_ARM64_PAUTH_KEY_IB = 1;
+    public static final int UC_ARM64_PAUTH_KEY_DA = 2;
+    public static final int UC_ARM64_PAUTH_KEY_DB = 3;
+    public static final int UC_ARM64_PAUTH_KEY_GA = 4;
+    public static final int UC_ARM64_PAUTH_KEY_ENDING = 5;
+
 }
diff --git a/bindings/java/src/main/java/unicorn/UnicornConst.java b/bindings/java/src/main/java/unicorn/UnicornConst.java
@@ -149,6 +149,9 @@ public interface UnicornConst {
     public static final int UC_CTL_TLB_TYPE = 12;
     public static final int UC_CTL_TCG_BUFFER_SIZE = 13;
     public static final int UC_CTL_CONTEXT_MODE = 14;
+    public static final int UC_CTL_PAUTH_SIGN = 15;
+    public static final int UC_CTL_PAUTH_STRIP = 16;
+    public static final int UC_CTL_PAUTH_AUTH = 17;
     public static final int UC_CTL_CONTEXT_CPU = 1;
     public static final int UC_CTL_CONTEXT_MEMORY = 2;
 
diff --git a/bindings/pascal/unicorn/Arm64Const.pas b/bindings/pascal/unicorn/Arm64Const.pas
@@ -338,5 +338,14 @@ interface
   UC_ARM64_INS_WFI = 5;
   UC_ARM64_INS_ENDING = 6;
 
+// ARM64 PAuth keys
+
+  UC_ARM64_PAUTH_KEY_IA = 0;
+  UC_ARM64_PAUTH_KEY_IB = 1;
+  UC_ARM64_PAUTH_KEY_DA = 2;
+  UC_ARM64_PAUTH_KEY_DB = 3;
+  UC_ARM64_PAUTH_KEY_GA = 4;
+  UC_ARM64_PAUTH_KEY_ENDING = 5;
+
 implementation
 end.
diff --git a/bindings/pascal/unicorn/UnicornConst.pas b/bindings/pascal/unicorn/UnicornConst.pas
@@ -150,6 +150,9 @@ interface
   UC_CTL_TLB_TYPE = 12;
   UC_CTL_TCG_BUFFER_SIZE = 13;
   UC_CTL_CONTEXT_MODE = 14;
+  UC_CTL_PAUTH_SIGN = 15;
+  UC_CTL_PAUTH_STRIP = 16;
+  UC_CTL_PAUTH_AUTH = 17;
   UC_CTL_CONTEXT_CPU = 1;
   UC_CTL_CONTEXT_MEMORY = 2;
 
diff --git a/bindings/python/unicorn/arm64_const.py b/bindings/python/unicorn/arm64_const.py
@@ -332,3 +332,12 @@
 UC_ARM64_INS_SYSL = 4
 UC_ARM64_INS_WFI = 5
 UC_ARM64_INS_ENDING = 6
+
+# ARM64 PAuth keys
+
+UC_ARM64_PAUTH_KEY_IA = 0
+UC_ARM64_PAUTH_KEY_IB = 1
+UC_ARM64_PAUTH_KEY_DA = 2
+UC_ARM64_PAUTH_KEY_DB = 3
+UC_ARM64_PAUTH_KEY_GA = 4
+UC_ARM64_PAUTH_KEY_ENDING = 5
diff --git a/bindings/python/unicorn/unicorn_const.py b/bindings/python/unicorn/unicorn_const.py
@@ -145,5 +145,8 @@
 UC_CTL_TLB_TYPE = 12
 UC_CTL_TCG_BUFFER_SIZE = 13
 UC_CTL_CONTEXT_MODE = 14
+UC_CTL_PAUTH_SIGN = 15
+UC_CTL_PAUTH_STRIP = 16
+UC_CTL_PAUTH_AUTH = 17
 UC_CTL_CONTEXT_CPU = 1
 UC_CTL_CONTEXT_MEMORY = 2
diff --git a/bindings/python/unicorn/unicorn_py3/unicorn.py b/bindings/python/unicorn/unicorn_py3/unicorn.py
@@ -1474,6 +1474,58 @@ def ctl_set_tcg_buffer_size(self, size: int) -> None:
             (ctypes.c_uint32, size)
         )
 
+    def ctl_pauth_sign(self, ptr: int, key: int, diversifier: int) -> int:
+        """Sign a pointer with a key and discriminator.
+
+        Args:
+            ptr: pointer to sign
+            key: architecture-specific constant indicating the key to use
+            diversifier: discriminator to use
+
+        Returns: the signed pointer
+        """
+
+        return self.__ctl_wr(uc.UC_CTL_PAUTH_SIGN,
+            (ctypes.c_uint64, ptr),
+            (ctypes.c_uint32, key),
+            (ctypes.c_uint64, diversifier),
+            (ctypes.c_uint64, None),
+        )
+
+    def ctl_pauth_strip(self, ptr: int, key: int) -> int:
+        """Strip the PAC from a possibly signed pointer.
+
+        Args:
+            ptr: pointer to strip PAC from
+            key: architecture-specific constant indicating the key to use
+
+        Returns: the stripped pointer
+        """
+
+        return self.__ctl_wr(uc.UC_CTL_PAUTH_STRIP,
+            (ctypes.c_uint64, ptr),
+            (ctypes.c_uint32, key),
+            (ctypes.c_uint64, None),
+        )
+
+    def ctl_pauth_auth(self, ptr: int, key: int, diversifier: int) -> bool:
+        """Authenticate a pointer with a key and discriminator.
+
+        Args:
+            ptr: signed pointer to authenticate
+            key: architecture-specific constant indicating the key to use
+            diversifier: discriminator to use
+
+        Returns: True if signature is valid, False othewise
+        """
+
+        return self.__ctl_wr(uc.UC_CTL_PAUTH_AUTH,
+            (ctypes.c_uint64, ptr),
+            (ctypes.c_uint32, key),
+            (ctypes.c_uint64, diversifier),
+            (ctypes.c_bool, None),
+        )
+
 
 class UcContext(RegStateManager):
     """Unicorn internal context.
diff --git a/bindings/ruby/unicorn_gem/lib/unicorn_engine/arm64_const.rb b/bindings/ruby/unicorn_gem/lib/unicorn_engine/arm64_const.rb
@@ -334,4 +334,13 @@ module UnicornEngine
 	UC_ARM64_INS_SYSL = 4
 	UC_ARM64_INS_WFI = 5
 	UC_ARM64_INS_ENDING = 6
+
+# ARM64 PAuth keys
+
+	UC_ARM64_PAUTH_KEY_IA = 0
+	UC_ARM64_PAUTH_KEY_IB = 1
+	UC_ARM64_PAUTH_KEY_DA = 2
+	UC_ARM64_PAUTH_KEY_DB = 3
+	UC_ARM64_PAUTH_KEY_GA = 4
+	UC_ARM64_PAUTH_KEY_ENDING = 5
 end
diff --git a/bindings/ruby/unicorn_gem/lib/unicorn_engine/unicorn_const.rb b/bindings/ruby/unicorn_gem/lib/unicorn_engine/unicorn_const.rb
@@ -147,6 +147,9 @@ module UnicornEngine
 	UC_CTL_TLB_TYPE = 12
 	UC_CTL_TCG_BUFFER_SIZE = 13
 	UC_CTL_CONTEXT_MODE = 14
+	UC_CTL_PAUTH_SIGN = 15
+	UC_CTL_PAUTH_STRIP = 16
+	UC_CTL_PAUTH_AUTH = 17
 	UC_CTL_CONTEXT_CPU = 1
 	UC_CTL_CONTEXT_MEMORY = 2
 end
diff --git a/bindings/zig/unicorn/arm64_const.zig b/bindings/zig/unicorn/arm64_const.zig
@@ -335,4 +335,13 @@ pub const arm64Const = enum(c_int) {
 	ARM64_INS_WFI = 5,
 	ARM64_INS_ENDING = 6,
 
+// ARM64 PAuth keys
+
+	ARM64_PAUTH_KEY_IA = 0,
+	ARM64_PAUTH_KEY_IB = 1,
+	ARM64_PAUTH_KEY_DA = 2,
+	ARM64_PAUTH_KEY_DB = 3,
+	ARM64_PAUTH_KEY_GA = 4,
+	ARM64_PAUTH_KEY_ENDING = 5,
+
 };
diff --git a/bindings/zig/unicorn/unicorn_const.zig b/bindings/zig/unicorn/unicorn_const.zig
@@ -147,6 +147,9 @@ pub const unicornConst = enum(c_int) {
 	CTL_TLB_TYPE = 12,
 	CTL_TCG_BUFFER_SIZE = 13,
 	CTL_CONTEXT_MODE = 14,
+	CTL_PAUTH_SIGN = 15,
+	CTL_PAUTH_STRIP = 16,
+	CTL_PAUTH_AUTH = 17,
 	CTL_CONTEXT_CPU = 1,
 	CTL_CONTEXT_MEMORY = 2,
 
diff --git a/include/uc_priv.h b/include/uc_priv.h
@@ -157,6 +157,11 @@ typedef uc_tcg_flush_tlb uc_tb_flush_t;
 
 typedef uc_err (*uc_set_tlb_t)(struct uc_struct *uc, int mode);
 
+// PAuth sign and strip
+typedef uc_err (*uc_pauth_sign_t)(struct uc_struct *uc, uint64_t ptr, int key, uint64_t diversifier, uint64_t *signed_ptr);
+typedef uc_err (*uc_pauth_strip_t)(struct uc_struct *uc, uint64_t ptr, int key, uint64_t *stripped_ptr);
+typedef uc_err (*uc_pauth_auth_t)(struct uc_struct *uc, uint64_t ptr, int key, uint64_t diversifier, bool *valid);
+
 struct hook {
     int type;       // UC_HOOK_*
     int insn;       // instruction for HOOK_INSN
@@ -313,6 +318,9 @@ struct uc_struct {
     uc_tb_flush_t tb_flush;
     uc_add_inline_hook_t add_inline_hook;
     uc_del_inline_hook_t del_inline_hook;
+    uc_pauth_sign_t pauth_sign;
+    uc_pauth_strip_t pauth_strip;
+    uc_pauth_auth_t pauth_auth;
 
     uc_context_size_t context_size;
     uc_context_save_t context_save;
diff --git a/include/unicorn/arm64.h b/include/unicorn/arm64.h
@@ -387,6 +387,16 @@ typedef enum uc_arm64_insn {
     UC_ARM64_INS_ENDING
 } uc_arm64_insn;
 
+//> ARM64 PAuth keys
+typedef enum uc_arm64_pauth_key {
+    UC_ARM64_PAUTH_KEY_IA = 0,
+    UC_ARM64_PAUTH_KEY_IB,
+    UC_ARM64_PAUTH_KEY_DA,
+    UC_ARM64_PAUTH_KEY_DB,
+    UC_ARM64_PAUTH_KEY_GA,
+    UC_ARM64_PAUTH_KEY_ENDING,
+} uc_arm64_pauth_key;
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/include/unicorn/unicorn.h b/include/unicorn/unicorn.h
@@ -605,6 +605,46 @@ typedef enum uc_control_type {
     // controle if context_save/restore should work with snapshots
     // Write: @args = (int)
     UC_CTL_CONTEXT_MODE,
+
+    // Sign a pointer with a given architecture-specific key and a diversifier
+    // (also known as modifier, extra data, or discriminator).  If the key is
+    // currently disabled, the operation returns the unsigned ptr.
+    // ABI-specific string hashing or address blending is up to the caller to
+    // implement.
+    //
+    // Pointer authentication needs to have been set up properly beforehand.
+    // Depending on architecture, current CPU state may determine pointer
+    // layout and other aspects of the operation not explicitly specified as
+    // parameters.
+    //
+    // Read/write: @args = (uint64_t ptr, int key, uint64_t diversifier,
+    //                      uint64_t *signed_ptr)
+    UC_CTL_PAUTH_SIGN,
+
+    // Strip a possibly signed pointer of all PAC bits without authenticating,
+    // returning an unsigned pointer.
+    //
+    // Pointer authentication needs to have been set up properly beforehand.
+    // Depending on architecture, current CPU state may determine pointer
+    // layout and other aspects of the operation not explicitly specified as
+    // parameters.
+    //
+    // Read/write: @args = (uint64_t ptr, int key, uint64_t *stripped_ptr)
+    UC_CTL_PAUTH_STRIP,
+
+    // Authenticate a signed pointer with a given architecture-specific key and
+    // diversifier (also known as modifier, extra data, or discriminator).
+    // ABI-specific string hashing or address blending is up to the caller to
+    // implement.
+    //
+    // Pointer authentication needs to have been set up properly beforehand.
+    // Depending on architecture, current CPU state may determine pointer
+    // layout and other aspects of the operation not explicitly specified as
+    // parameters.
+    //
+    // Read/write: @args = (uint64_t ptr, int key, uint64_t diversifier,
+    //                      bool *valid)
+    UC_CTL_PAUTH_AUTH,
 } uc_control_type;
 
 /*
@@ -688,6 +728,12 @@ See sample_ctl.c for a detailed example.
     uc_ctl(uc, UC_CTL_WRITE(UC_CTL_TCG_BUFFER_SIZE, 1), (size))
 #define uc_ctl_context_mode(uc, mode)                                          \
     uc_ctl(uc, UC_CTL_WRITE(UC_CTL_CONTEXT_MODE, 1), (mode))
+#define uc_ctl_pauth_sign(uc, ptr, key, diversifier, signed_ptr)               \
+    uc_ctl(uc, UC_CTL_READ_WRITE(UC_CTL_PAUTH_SIGN, 4), (ptr), (key), (diversifier), (signed_ptr))
+#define uc_ctl_pauth_strip(uc, ptr, key, stripped_ptr)                         \
+    uc_ctl(uc, UC_CTL_READ_WRITE(UC_CTL_PAUTH_STRIP, 3), (ptr), (key), (stripped_ptr))
+#define uc_ctl_pauth_auth(uc, ptr, key, diversifier, valid)                    \
+    uc_ctl(uc, UC_CTL_READ_WRITE(UC_CTL_PAUTH_AUTH, 4), (ptr), (key), (diversifier), (valid))
 
 // Opaque storage for CPU context, used with uc_context_*()
 struct uc_context;
diff --git a/qemu/target/arm/pauth_helper.c b/qemu/target/arm/pauth_helper.c
@@ -492,3 +492,33 @@ uint64_t HELPER(xpacd)(CPUARMState *env, uint64_t a)
 {
     return pauth_strip(env, a, true);
 }
+
+uint64_t _uc_pauth_sign(CPUARMState *env, uint64_t ptr, uint64_t diversifier, uint32_t sctlr_bit, ARMPACKey *key, bool data)
+{
+    int el = arm_current_el(env);
+    if (!pauth_key_enabled(env, el, sctlr_bit)) {
+        return ptr;
+    } else {
+        return pauth_addpac(env, ptr, diversifier, key, data);
+    }
+}
+
+uint64_t _uc_pauth_sign_ga(CPUARMState *env, uint64_t ptr, uint64_t diversifier)
+{
+    return pauth_computepac(ptr, diversifier, env->keys.apga) & 0xffffffff00000000ull;
+}
+
+uint64_t _uc_pauth_strip(CPUARMState *env, uint64_t ptr, bool data)
+{
+    return pauth_strip(env, ptr, data);
+}
+
+bool _uc_pauth_auth(CPUARMState *env, uint64_t ptr, uint64_t diversifier, uint32_t sctlr_bit, ARMPACKey *key, bool data)
+{
+    int el = arm_current_el(env);
+    if (!pauth_key_enabled(env, el, sctlr_bit)) {
+        return false;
+    }
+    uint64_t maybe_corrupted_ptr = pauth_auth(env, ptr, diversifier, key, data, 0);
+    return maybe_corrupted_ptr == pauth_strip(env, ptr, data);
+}
diff --git a/qemu/target/arm/unicorn_aarch64.c b/qemu/target/arm/unicorn_aarch64.c
diff --git a/tests/unit/test_arm64.c b/tests/unit/test_arm64.c
diff --git a/uc.c b/uc.c
